The present invention relates to a novel calcium silicate water-treating agent useful in the treatment of industrial water or wastewater, boiler water, or other foul water containing sewage, feces, etc. and more particularly, to a calcium silicate water-treating agent capable of removing phosphorus compounds, such as phosphates and oxidisable pollutants which are measured in the determination of chemical oxygen demand (hereinafter such "oxidisable pollutants are referred to as "COD components".) from the water with a high efficiency, by a simple process that can be readily adapted to practical use.
The present invention further relates to a process for the water treatment with the novel water treating agent.
In recent years, environmental conservation and preservation of water have become increasingly a very important social problem and a higher level of technique and a more expanded utility have been progressively required in water treatment. In general, various sewages, foul water, industrial water or waste water, boiler water or the like contains inorganic phosphates, such as orthophosphoric acid or condensed phosphates in various forms, and, when water containing such phosphates is drained in nature, the phosphates considerably accelerate eutrophication in closed or stagnant water areas, such as lakes, marsh or inland sea, thereby causing serious problems.
Under such circumstances, there have heretofore been proposed various methods for treating various kinds of industrial wastewater, sewage and other foul water containing feces or other environmental pollutants and some of them have been practically used. For example, coagulation-sedimentation methods using lime or metallic salts such as aluminum salt, iron salt, or magnesium salt as a coagulating agent or precipitant; activated carbon adsorption; and activated sludge process are disclosed in the general introduction descriptions of Environmental Engineering, Volume 11, No. 11, pages 826, 834, 836 and 841 (1982), published by Environmental Conservation Engineering Association in Japan and in The Technology And Regulation of Pollution Control (Water Quality), pages 124, 128 and 187, published by Industrial Pollution Control Association on June 15, 1983 in Japan.
However, unfortunately, these known methods are not satisfactory as water treating methods because their ability to remove pollutants, especially phosphorus compounds and COD components, contained in waste water, is too low for practical use, and a great amount of treating agent is needed, thereby resulting a large amount of slurry and causing an increase in treatment time and cost. Further, sludge formed during the process of water treatment can not be readily precipitated by these prior art techniques and great care should be taken to handle treating agents. Further, these conventional methods have great difficulties in handling the sludge separated from water after treatment. In these treating methods, used water-treating agent is separated as sludge containing pollutants from water after treating. However, since in this separation operation, water adsorbed into the sludge can not be easily removed, great difficulties are experienced in the after-treating. For example, when the sludge is after-treated by incineration, much treatment cost is required. Alternatively, if the sludge is dumped, very strict limitations are imposed on the place where dumping occurs, since secondary pollution problems may be created.